JPH0255517A - Circuit breaker - Google Patents

Abstract

PURPOSE:To obtain a circuit breaker having a short time-limit advance alarm characteristic as well as a long time-limit preliminary alarm characteristic by detecting a main circuit current before it gets to the short time-limit region in the overcurrent tripping characteristics. CONSTITUTION:When the current flowing to a main circuit 5 exceeds e.g., 70% of the rated current, a long time-limit preliminary alarm circuit 20 supplies the value of a DC signal converted in an effective value from a maximum phase selection and effective value conversion circuit 8 to a preliminary alarm output circuit 21. When the current of the main circuit 5 exceeds e.g., 700% of the rated current, a short time-limit preliminary alarm circuit 30 supplies the value of a DC signal converted in a peak value from a maximum phase selection and peak value conversion circuit 7 to the preliminary alarm output circuit 21. As a result, this preliminary alarm output circuit 21, which excites a relay coil 24 and closes a normally open contact 24a, energizes a control power buzzer 26 to ring and turns ON a preliminary alarm operation displaying LED 25.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a circuit breaker, in particular, a circuit breaker, in particular, which detects a short circuit in the overcurrent trip characteristic before an overcurrent flows in its main circuit and the switching mechanism section is turned off. This invention relates to a circuit breaker that can detect a current before it reaches a time limit and issue a warning in advance.

[Prior Art] Fig. 3 is a block diagram showing a partial circuit diagram of a conventional circuit breaker disclosed in Japanese Patent Application No. 168,994/1983, and in the figure, 1 indicates an AC power source, for example, a three-phase AC power source. , 2 is a load supplied with power by this AC power source 1, and 3 is a circuit breaker connected between these AC power source 1 and the load 2.

This circuit breaker 3 includes a main circuit 5 consisting of three-phase conductors 5a, 5b, and 5c connected to an AC power source 1 via an opening/closing i structure 4, and each phase conductor 5a, 5b, and 5c of this main circuit 5. Current transformers CT a , CT b , respectively connected to
CT c, a rectifier circuit 6 connected to the secondary side of these current transformers, a maximum phase selection/peak value conversion circuit 7 and a maximum phase selection/effectiveness circuit connected individually to the output side of this rectification circuit 6. An instantaneous circuit 9 and a short time limit circuit 1 are individually connected to the output side of the value conversion circuit 8 and the maximum phase selection/peak value conversion circuit 7.
0, a long time limit circuit 11 connected to the output side of the maximum phase selection/effective value conversion circuit 8, and a trigger circuit connected to the output sides of the instantaneous circuit 9, the short time limit circuit 10, and the long time limit circuit 11]
2, a tripping coil 13 connected between both ends of the rectifier circuit 6 via the trigger circuit 12, and an overcurrent indicating LED 14 connected to the long time limit circuit 11. Note that the circuits 7 to 11 described above are made of dedicated ICs.

The circuit interrupter 3 is further connected to the output side of the maximum phase selection and effective value conversion circuit 8, and detects the main circuit current before reaching the long time limit region in the overcurrent tripping characteristic to issue a warning in advance. a long-time advance warning circuit 20 having a long-time advance warning characteristic for issuing a long-time advance warning circuit; and an advance warning output circuit 21 connected to the output side of the long-time advance warning circuit 20 and operated by the advance warning signal. A control power supply 23 of AC 100 volts, for example, is connected to the input side of the advance warning output circuit 21 via a voltage drop unit, for example, a transformer 22, and a control power supply 23 is connected to the output side of the advance warning output circuit 21 and is excited by the output thereof. relay coil 24 and its normally open contacts 24
．． a, an alarm generating means connected in parallel with the relay coil 24 and lit by the output of the advance alarm output circuit 2], for example, an advance alarm operation display LED 25, and a normally open contact 2.
Another alarm generating means connected between both ends of the control power supply 23 via 4a includes a buzzer 26.

FIG. 4 is a curve diagram showing the overcurrent tripping characteristics and advance warning characteristics of the circuit breaker 3 shown in FIG. The overcurrent trip characteristic A is, for example, 100% to 1000% of the rated current.
% long time range LTD, 1000% to 1700% short time range STD, and 1700% or more instantaneous range lN5
Consists of T. Further, advance warning characteristic B is a long time advance warning characteristic L for issuing a warning before the main circuit current exceeds, for example, 70% of the rated current but reaching the long time limit LTD.
Consists of TD-PAL.

The conventional circuit breaker 3 is constructed as described above, and its operation will be explained with reference to FIGS. 3 and 4. Assume now that the switching mechanism section 4 of the circuit breaker 3 is closed, that is, it is not tripped, and current is flowing from the AC power source 1 through the main circuit 5 to the load 2. Current transformer CT a
, CTb, and CTc allow a secondary current proportional to the main circuit current to flow through their secondary sides. The rectifier circuit 6 rectifies the AC secondary current of each of the three phases. The maximum phase selection and peak value conversion circuit 7 selects the maximum phase rectified signal from among the three phase rectified signals from the rectifier circuit 6, and converts it to a peak value.

Similarly, the maximum phase selection and effective value conversion circuit 8 selects the maximum phase rectified signal and converts it into an effective value.

The peak value-converted DC signal has the instantaneous region lN5T and short time limit region 5TI of the overcurrent tripping characteristics shown in Fig. 4, respectively.
The direct current signal supplied to the instantaneous circuit 9 and the short time limit circuit 10 having the characteristics R) and subjected to effective value conversion is applied to the long time limit region L
When the current flowing through the main circuit 5, which is supplied to the long time delay circuit 11 having the TD characteristic and the long time advance warning circuit 20 having the long time advance warning characteristic LTD-PAL, exceeds, for example, 70% of the rated current, The long time advance warning circuit 20 operates for a predetermined period of time, for example, in accordance with the value of the DC signal converted into the effective value from the maximum phase selection/effective value conversion circuit 8, that is, the long time advance warning characteristic LTD-PAL in FIG. After 40 seconds, an advance warning signal is supplied to the advance warning output circuit 21. Then, the advance warning output circuit 21 excites the relay coil 24 to close its normally open contact 24a, and the control power supply 23 turns on the buzzer 26.
energizes this and makes it sound, and the L for advance warning operation display.
Turn on ED25.

The main circuit current becomes even larger, e.g. 100% of the rated current.
%, the long time limit circuit 11 outputs an output and turns on the trigger circuit 12 after a predetermined time shown in FIG. At the same time, the overcurrent display LED 14 is turned on. When the trigger circuit 12 turns on, the tripping coil 1
3 is excited by the rectified output of the rectifier circuit 6, and opens the opening/closing mechanism section 4 to cut off the main circuit current. Similarly, the main circuit current becomes larger and larger, e.g. 1000% of the rated current.
, 1700%, the short time limit circuit 10 and the instantaneous circuit 9 output their respective outputs, and the main circuit current is interrupted.

[Problems to be Solved by the Invention] The conventional circuit disconnection switch as described above has a problem in that it only has a long-time advance warning characteristic.

The present invention has been made to solve these problems, and an object of the present invention is to provide a circuit breaker having short-time advance warning characteristics in addition to long-time advance warning characteristics.

[Means for Solving the Problems] The circuit breaker and disconnector according to the present invention has a short circuit for detecting the main circuit current before reaching the short time limit region in the overcurrent trip characteristic and issuing a warning in advance. A short-time advance warning circuit with time-limit advance warning characteristics is installed.

[Function] In the present invention, when the short-time advance warning circuit having the short-time advance warning characteristic detects the main circuit current before reaching the short time limit region, it generates an advance warning signal, and the circuit is activated by this advance warning signal. The relay coil is excited by the output of the advance warning output circuit, which in turn sounds the buzzer and lights up the advance warning operation display LED.

[Embodiment] Fig. 1 is a block diagram partially showing an embodiment of the present invention as a circuit diagram.
is exactly the same as shown in FIG. The circuit breaker 3A of the present invention is further connected to the output side of the maximum phase selection and peak value conversion circuit i\87, and detects the main circuit current before reaching the short time region in the overcurrent tripping characteristic. A short-time advance warning circuit 30 having a short-time advance warning characteristic for issuing a warning in advance is provided, and the output side of this short-time advance warning circuit 30 is also connected to the advance warning output circuit 21.

FIG. 2 is a curve diagram showing the overcurrent tripping characteristics and advance warning characteristics of the circuit breaker 3A of the present invention. Is the overcurrent trip characteristic A exactly the same as shown in Figure 4?
The advance warning characteristic BA is the long time advance warning characteristic LTD-P.
In addition to AL, if the upper circuit current is, for example, 700% of the rated current
Short-time advance warning characteristic S T D -P to issue an alarm before exceeding S T i) or reaching the short time limit S T i)
Consists of A and L.

In the circuit breaker 3A of the present invention shown in FIG.
When the current flowing through the main circuit 5 exceeds, for example, 70% of the rated current, the long time advance warning circuit 20 activates the value of the DC signal converted into the effective value from the maximum phase selection/effective value conversion circuit 8, that is, the second Long time advance warning characteristic L T D-P A
A pre-warning signal is supplied to the pre-warning output circuit 21 after a predetermined period of time, for example 40 seconds, in accordance with L. Further, when the main circuit current exceeds, for example, 700% of the rated current, the short-time advance warning circuit 30 selects the peak value from the maximum sum selection/peak value conversion circuit 7! An advance warning signal is supplied to the advance warning output circuit 21 after a predetermined period of time, for example, 18 seconds, in accordance with the value of the converted DC signal, that is, the short-time advance warning characteristics S and TD-PAL shown in FIG. As a result, this advance warning output circuit 21 excites the relay coil 24 and makes its normally open contact 2
4a, energizes the control power supply 23 or the buser 26 so that it does not sound, and also turns on the LED for displaying advance warning operation.
Turn on 25. Note that the overcurrent tripping operation is as described above with reference to FIG.

[Effects of the Invention] As described in detail above, the present invention is equipped with a short-time advance warning circuit having a short-time advance warning characteristic for issuing a long-time warning, so that the overcurrent tripping characteristic is In addition to the long time limit LTD, a warning can be issued in advance for the short time limit STD to notify the operator.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a partial circuit diagram of an embodiment of the present invention, FIG. 2 is a curve diagram showing the characteristics of the circuit disconnector of the present invention, and FIG. 3 is a conventional circuit diagram showing the characteristics of the circuit disconnector. FIG. 4 is a block diagram showing a part of the circuit breaker, and FIG. 4 is a curve diagram showing the characteristics of a conventional circuit breaker. In the figure, 1 is an AC power supply, 2 is a load, 3A is a circuit breaker, 4 is a switching mechanism, 5 is a main circuit, 9 is an instantaneous circuit, 1
0 is a short time limit circuit, 11 is a long time limit circuit, 13 is a tripping coil, 20 is a long time advance warning circuit, 21 is an advance warning output circuit, 25 is an LED for advance warning operation display, 26 is a buzzer, and 30 is a short time limit circuit. This is a time-limited advance warning circuit. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] In a circuit disconnector having an overcurrent tripping characteristic for detecting an overcurrent flowing in a main circuit between an AC power source and a load and disconnecting the main circuit, the overcurrent tripping characteristic includes: A long time advance warning circuit having a long time advance warning characteristic for detecting the current before reaching the long time limit region and issuing a warning in advance; and a long time advance warning circuit having a long time advance warning characteristic before reaching the short time limit region in the overcurrent trip characteristic. a short-time advance warning circuit having a short-time advance warning characteristic for detecting the current of the current and issuing a warning in advance, and an advance warning output circuit operated by advance warning signals from both of these advance warning circuits; A circuit breaker characterized in that it is equipped with an alarm generation means activated by the output of the advance alarm output circuit.